Apparatus for treating blood



March 30, 1965 w. c. LING 3,175,555

APPARATUS FOR TREATING BLOOD Filed Sept. 21, 1962 2 Sheets-Sheet 1 BLOOD I Inventor Wilfred C. 1.111% B H. M a 2/ flfiorneg/ March 30, 1965 w. c. LING 3,175,555

APPARATUS FOR TREATING BLOOD Filed Sept. 21, 1962 2 Sheets-Sheet 2 INVENTOR WILFRED C. LING ATTORNEY United States Patent 5,555 APPARATUS FOR TREATING BLOOD Wilfred C. Ling, Waukegan, 111., assignor to Abbott Laboratories, Chicago, Ill., a corporation of Illinois Filed Sept. 21, 1962,Ser. No. 225,423 2%) Claims. (Cl. 128-214) The present invention relates to an apparatus for treating blood outside the body of an individual, such apparatus sometimes being referred to as an artificial lung.

This application is a continuation-in-part of application Serial No. 19,138, filed March 14, 1960, and now abandoned.

In various types of surgical operations, it may be necessary, or there may be substantial advantage, to isolate the heart or other parts of the body from the blood circulation system. In this extracorporeal circulation system, venous blood is pumped through a blood pump to an oxygenating apparatus where the blood is oxygenated. The oxygenated blood is then returned to the main circulation system of the body. The apparatus for oxygenating the blood outside the patients body is often referred to as an artificial lung because it supplants the functions of the lungs of a patient.

The process of oxygenating blood requires that oxygen be brought into intimate contact with the venous blood, while at the same time, providing for the removal of carbon dioxide which is a product of the body metabolism. It is of extreme importance that the blood being returned to the patient have no entrained gas, e.g., oxygen. Thus, the artificial lung must be capable of oxygenating the blood and of removing carbon dioxide and any unreacted oxygen from the blood.

This invention provides a type of oxygenation in which venous blood is brought into intimate contact with numerous oxygen bubbles which oxygenate as well as purge the carbon dioxide from the blood.

A principal object of the invention is to provide a simple, efficient and inexpensive apparatus for oxygenation of blood using the aforementioned principle.

Other objects and advantages of the invention include the provision of an efiic-ient defoaming system employing a negligible amount of defoaming agent; an apparatus for producing a large number of oxygen bubbles in a small volume of blood, thus providing efficient and uniform oxygenation; an apparatus in which the blood is exposed to a large number of oxygen bubbles with very low pressure and velocity, thus reducing the damage to the blood elements to a minimum; an apparatus in which fibrins, gas bubbles or other particles, if present, are filtered out through two filters operating in series as part of the oxygenator; an apparatus in which the blood volume is constantly indicated by graduation marks on the rigid and transparent plastic wall; an apparatus made sterile and disposable, thus eliminating the risk of inadequate cleaning and sterilization; and an apparatus due to its rigid nature can be partially submerged in a bath for maintaining temperature control.

Bubbling of oxygen through blood inherently creates foaming which is a physical mixture of gas bubbles and blood. Foaming is both damaging to the blood elements and a dangerous source of gas embolism if allowed to enter the blood stream. It is, therefore, of utmost importance that an oxygenator should allow the minimum of foaming and absolutely no entrained bubbles to enter the blood circulation system. Therefore, an artificial lung must not only break the foam occurring in the oxygenation step, but, also, must handle the blood in a manner so as not to create further froth. The apparatus rapidly breaks the foam and prevents the carryover of any entrained bubbles to the exit of the appara- 3,175,555 Patented Mar. 30, 1965 tus. The apparatus of the invention employs a flooded system. By a flooded system is meant that as compared to prior art practices where thin layers of blood were handled in the apparatus, the apparatus is adapted to maintain a substantial depth of blood so that the blood is moved from one stage to the next at a point below the surface of the blood.

Thus the apparatus enables the blood to be efficiently and uniformly oxygenated by means of a novel bubbling system, and to have the carbon dioxide and entrained bubbles removed therefrom without such a plethora of foam being created as to defeat desired advantages of high efliciency oxygenation. This reduces the total amount of blood which the system requires for its operation.

A further object and advantage lies in the filtering which is carried out in this oxygenator system. In the embodiments hereinafter described it will be seen that the filtering is performed by moving the blood horizontally through a generally vertical screen. One effect of this is to allow any entrained bubbles to escape upward. Another effect is to enable rapid filtration by providing a large filtering surface for small as well as large volumes of blood during filtering. Still another effect is that should the screen commence to clog under the conditions of its use in any specific instance, the reduced flow through the portion of the screen initially used will not make it necessary to change the filter or to employ a new piece of apparatus to keep the patient supplied. Instead the eifect will be to raise the blood level in the filtering chambers so that a new portion of the filtering screen is put into use. The use of a small amount of blood to the system may facilitate the raising of the blood level and, thus, the use of new, unused, screen area.

FIGURE 1 is a side elevational view of an artificial lung embodying the concepts of the present invention with parts broken away and in vertical section to better illustrate the contents thereof and with arrows indicating the direction of the flow of blood therein;

FIGURE 2 is a perspective view of the screen element employed in the device of FIGURE 1;

FIGURE 3 is a perspective view of the oxygen disersing element employed in the apparatus of FIGURE 1; FIGURE 4 is a rear view of the present apparatus with arrows indicating the flow of blood therethrough;

FIGURE 5 is a longitudinal, sectional view taken along line 5-5 of FIGURE 4; and

FIGURE 6 is a horizontal sectional view of a modified embodiment of the present invention.

Essentially, minute finely dispersed, bubbles of oxygen are bubbled through the blood to obtain as intimate a contact as possible between the oxygen and the blood, while at the same time allowing the carbon dioxide in the blood to escape along with unused oxygen. All this is done with the minimum of turbulence and, therefore, minimum damage to the blood elements. After a preliminary defoaming, i.e., release of majority of the oxygen not chem- 1cally reacted with the blood, the blood is allowed to flow to a filtering zone for the elimination of any fibrinous matters and remaining gas bubbles. It is important to suppress the formation of the foam in the first place and to cause the blood to flow in a manner such as to avoid transfer of the foam from the oxygenation zone and to prevent the creation of additional foam during flowing of the blood. Several features of the apparatus are directed to accomplishing this result. In the first place, the blood from the oxygenation zone is allowed to flow through a defoaming zone to the filtering zone by a reversal of direction of flow downwardly and below the surface level of the blood in the defoarning zone. This, in itself, acts to reduce foam carry-over into the filtering zone.

a; 7 7 o 7 7 In-additionto this however, the blood is caused to flow a in such a way that contact is made with a material in the defoaming zone; The material is treated with a surface active agent; This: agent, which is 'insoluble'in blood, raises the surface tension of the blood and, thus, breaks and; suppressestheformation of foam. This action is magnified by utilizing a relatively large. contact areabetween the surface-active materialan' dth'e blood.

Inthefiltering zone the. blood is moved in a horizontal direction with continuous, even, flow being maintained. This avoidsthe creation of additional foam.

During this flow in the. filtering zone, the'blood is passed.

through a filter to remove any fibrinous materials and entrained bubbles. While the screening need not necessarily be performedhorizontally, i.e., through a screen positioned generally vertical, this proves to be a desirable manner in Whichto do it and still maintain thesmooth, even, flow. The screen can be positioned horizontally, but because a designated volume of blood must be maintained about the screen and because of the tendency to trap gas under the screen, there is no advantage in employing a horizontal screen, but rather there is preferably employed a vertical screen. The use of a vertical screen also allows for filtering at all heights of the screen and, therefore, a small or large volume of blood can be handled by the same apparatus.

While one such screen for debubbling and filtering is sufficient, it is'preferred to allow the blood'to flow into and through a second similar treatment zone in a corresponding manner. The use of a plurality of treatment zonesis a wise safety precaution. Inflowing the blood from the first to the. second treatment zone, the blood is withdrawn from the first'zone ata point below the surface level of the blood in that zone-and the blood is introduced into the second treatment zone at a point below the level of. the blood in the second zone. The flow of the blood into and through the second treatment zone is with the same apparent quiescence as referred to' with respect to the first zone. In the second zone, the blood is again filtered in the manner described with respect to thefirst zone. The blood iswithdrawn from the second standpipe portion 14 is packing 17 which is an open knit material coated with a blood-defoaming agent comprised of polymeric dimethyl siloxane and silicon dioxide. Packing 17 employed in this instance isa plastic material comprised of polyvinylidene chloride and polyvinylchloride resins commonly known as Saran. It is of a loose mesh construction allowing for maximum flow of blood therethrough, while also providing maximum surface contact between the defoaming agent placed on the packing and the blood. The coated packing 17 thereby serves as a surface-active defoaming means.

A circular cover 18 is provided a short distance inwardly from the top of column 10. Cover 18 has a gas vent projection 19 therein; A filter plug. 2% with passageway 21 is placed over gas vent'19 and has a piece of sterile cotton 22 placed therein for sterility purposes.

treatment zone at'a pointbelow the surface level of the 1 blood therein. The withdrawn blood is in condition to a the foregoing purpose. FIGURES 15 illustrate an em bodiment-of an artificiallung intended tobe disposable and utilized only once. The invention refers'to an artificial lung that can be manufactured and sterilized relatively inexpensively, and, yet, one that has proven to do anexcellent job. It comprises'an oxygenating column 7 13, with an oxygenatin gi membrane 27 therein, which dis charges into a defoaming column 10. In juxtaposition with the defoamingcolumn, is a firstfilter chamber 11 which defines thefi'rsttreatment zone and a second filter chamber 12 which defines the second treatment zone.

Inone embodiment of the invention, illustrated in FIGURES 1 5, the oxygenator or apparatus generally indicated at 95 is of unitary construction'and has a-cylindrical defoaming column 10. In communication with column 1%), is a first rectangular filter chamber 11 which is laterally attachedrto the column. A second rectangular filterchamber 12, communicates with chamber 11, and both chambers are laterally attached to each other and positioned'in a longitudinal manner with respect to col- Near. the base portion 104 of cylindrical column 10 and extending'through the adjacent base portion 11a of the rounded side of chamber 11, as well as the front semicircular wall 2410f column 10, is a tubular, tapering oxygenated blood conduit 25, providing a passageway between column 10 and filter chamber 11; The oxygenated blood conduit 25 also has an exterior portion molded into the front wall 23. of chamber 11. V

A filter screen, generally indicated at. 41, as shown in FIGURE 2, is accommodated in rectangular alignment by both chambers 11 and 12. Screen 41 is comprised of a rectangular supporting frame 42 and is composed of a semi-rigid polyethylene material having an integral supporting rib 43, of the same composition, disposed equidistant from the ends of the frame A duel section frame is thereby formed to which is secured nylon filtering screen material 44 and 45. Portions of two of these filter screens are shown in chambers 11 and 12 in FIGURE 1. Screening material 44a and 44b issupported by frames 42a and 42bin chambers 11 and 12, respectively.

Dimples 30 and 31 are molded into the front walls 23 and -32 of chambers 11 and 12, respectively, and project a short distance inwardly to 'hold screening material 44a and 44b,respectively, spaced from the front walls of the respective chambers. Near the top of the chamber 11 and molded intofront wall 23 are auxiliary blood inlet passages 33 and 34, covered by filter plugs 35 and 36, respectively, similar to filter plug 20 on gas vent 19.

V A circular outlet portion 37 is disposed near the base of chamber 12 and is molded in the front Wall 32 thereof communicating with outlet tube 58.

FIGURE 3 illustrates an oxygen disperser. generally indicated at. 39 composed of a circular body section 26 having the oxygenating membrane 27 placed transversely across the. inside of the body section. Membrane 27 is composed of a porous polyvinylchloride material. As illustrated in FIGURE 1, body section 26 is accommodatedinside oxygenating tube 13 a short distance inwardly from the lower end thereof. One end of blood inlet tube 15 is axiallydisposed in body section-26 and communicates with upstanding conduit 23. The upperend of conduit 28 contacts the lower surface of membrane 27 and is aligned withpassageway 40 in membrane 27. Oxybrane Z'Tand a uniform distribution of .oxygen is thereby 1 effected inthe blood rising in oxygenating tube 13.

Referring to FIGURE ,4 it will be noted that a pair rear walls 48 and 49 of filter chambers 11 and 12, respec tively. Gas vents 46 and 47 are provided with filter plugs 50 and 51, respectively, similar to filter plug 20 in vent 19.

Extending between the adjacent rear walls 48 and 49 of chambers 11 and 12 and communicating with filter chambers 11 and 12, is a flexible conduit 52 spaced a short distance from the bottom of the chamber. A tapering tubular passageway 53 is spaced a short distance from the conduit 52. A third tubular passageway 54 is placed about midway between the top and bottom of chambers 11 and 12. Each of the passageways 52-54 provide communi cation between chambers 11 and 12 at the rear thereof. Passageways 53 and 54 are molded into rear walls 48 and 49 of chambers 11 and 12, respectively and also communicate through the rounded, adjacent sides of chambers 11 and 12. Dimples 55 and 56 are molded in rear Walls 48 and 49, respectively, and with oppositely disposed dimples 30 and 31, serve to hold screening material 440; and 44b spaced from the respective sides of the respective chambers.

Two tabular projections 57 and 58, which are in effect extensions of the upper surface of the oxygenator extend a short distance along the lateral edges and serve as attachment means for supporting hooks 59 and 60, respectively.

As viewed in FIGURE 5, filter chamber 12, and likewise chamber 11 which is a duplication of chamber 12, has two oppositely disposed front and rear walls 32 and 49, respectively, diverging outwardly from the top to form the largest cross-section for the chamber at a point midway between the top and bottom of the chambers and then converging again as they approach the bottom of the chamber where the sides are substantially parallel. It will be noted that tubular passageway 54 extends through the djacent lateral sides of chambers 11 and 12 at the point of its greatest cross-section, the purpose of which will be later explained. Passageways 52 and 53 extend through the adjacent lateral walls at a point where the chamber is of smaller cross-section. Dimple 31 in front Wall 32 and oppositely disposed dimple 56 in back wall 49 of chamber 12 serve to hold screening material 44!: away from the respective sides of the chamber. Screening material 44b is supported by frame 42b and supporting rib 43b. Screening material 45b is supported in the upper portion of frame 421) to form a filter screen generally 41b of the same type described generally by numeral 41 in FIGURE 3. It will be observed that screen 41!) divides chamber 12 into two side-by-side compartments. Chamber 11 is likewise divided by a similar screen as indicated in reference to FIGURE 1.

The modified embodiment of the present invention illus trated in FIGURE 6 comprises the same parts described in the lung of FIGURES 1-5, the reference characters to like components being primed. It includes cylindrical defoaming column 64. Filter chambers 65 and 66 have front and rear walls 67, 69 and 68, 70, respectively, and are connected in series to column 64. In this embodiment the front and rear walls are of the same dimension as the front and rear walls of chambers 11 and 12. The walls are spaced from each other to provide the required cubic capacity for chambers 65 and 66. On the modified embodiment a unitary sheet of nylon screening material 71 is sealed between the walls of chambers 65 and 66, thereby serving the same purpose as the placement of a filter screen in each chamber, one of which is generally described by numeral 41 in FIGURE 2.

A further modification can be made of the oxygenator by providing only one filter chamber with the outlet means disposed in the rear wall.

' The oxygenator is preferably formed of a transparent, rigid polyvinylchloride material and is fabricated in two half-sections as will be best observed in FIGURE 6. One half-section is comprised of the front semi-circular wall 24 of column and the front Walls 23 and 32, of the chambers 11 and 12, respectively. The other half-see tion comprises the rear semi-circular wall 72 of column 10 and the rear walls 48 and 49 of chambers 11 and 12, respectively. The previously described passageways, air vents, and dimples are formed in the respective walls of the oxygenator. The oxygen disperser generally indicated at 39 is preassembled with tubes 15 and 16 sealed therein, the tubes being extruded from a flexible polyvinylchloride material. Disperser generally 39 is then sealed in the lower end of tube 13 with membrane 27 disposed transversely in relation to tube 13. A substantial portion of the opened end of oxygenating tube 13 is placed in one half'section of column 10. One end of blood outlet tube 33 extruded of the same material as tube 13 is placed in contact with circular outlet portion 37. Filter screen, shown generally by 41b is placed in rectangular alignment with either the front or rear walls of chamber 12. A second filter screen of the same type as 41 or 41b is placed in rectangular alignment with either the front or rear walls of chamber 11. The respective walls of one half-section are then placed in face-to-face relationship with the respective walls of the other half-section and the two half-sections are electronically sealed together. The two screens are sealed therebetween by means of a marginal web 73 formed along the outer edges of the oxygenator sealing tube 13 therein. An intermarginal web 73a is also formed defining two independent filter chambers 11 and 12. Outlet tube 38 is likewise sealed to outlet portion 37. Packing 17 lightly coated with a blood defoaming agent is placed in column 10. The cover 18 is sealed therein. The filter plug 20 as well as filter plugs 33, 34 for auxiliary blood inlet passages 35 and 36, respectively, and plugs 50, 51 for vents 46 and 47 are placed on the respective openings.

In constructing the apparatus 9 it is obvious that membrane 27 of disperser generally indicated at 39 can be directly sealed to the wall of tube 13. Blood inlet tube 15 can be sealed directly to membrane 27 in communication with passageway 40. The end of tube 13 can be sealed off with the end of oxygen inlet tube 16 placed between membrane 27 and the sealed end of tube 13.

The apparatus 9A illustrated in FIGURE 6 is composed in the same foregoing manner except that a unitary sheet of nylon filter material 71 is sealed between the front and rear walls 67, 69 and 68, 70 along the marginal edges of chambers 11 and 12, respectively, in place of the two independent filter screens.

To employ the apparatus 9 a suitable frame or support is provided into which hooks 59 and 60 engage. Venous blood is pumped by means of a suitable pump (not shown) or the like through inlet tube 15 and through passageway 49 of membrane 27. Oxygen under suitable pressure from a source (not shown) is introduced into tube 13 from oxygen inlet tube 16. As the oxygen enters oxygenating tube 13 it is dispersed by means of membrane 27 thereby giving uniform dispersion of the oxygen as it leaves the upper surface of membrane 27 and bubbles uniformly upwardly through the ascending blood. While the blood is being oxygenated, it flows upwardly through oxygenating tube 13 and into column 16 where it contacts packing 17. Packing 17, lightly coated with the previously described defoaming material, acts to break and/or suppress the formation of foam. As the blood is contacting packing 17 it flows downwardly around standpipe portion 14 with negligible velocity with respect to the large surface area of the packing 17, thus eliminating the danger of carrying off the defoaming agent. The blood then flows into chamber 11 through tubular oxygenated blood conduit 25 where it flows in the direction of the back wall 48 of chamber 11 and through filter screen 44a. The filtered blood leaves chamber 11, under normal flow, by means of passageway 53, connecting chambers 11 and 12 in series, and flows into chamber 12. A flexible conduit 52 connecting chambers 11 and 12 is normally clamped-off during operation by a pinch clamp 52a. When it is desired to drain the ap- 'Wall 32 of the chamber.

'trol. indication'marking can also be placed on the chambers,

paratus 9 or when the apparatus 9 is employed to oxy genate the: blood ofan infant or for isolated perfusion of a portion-of a body, the pinch clamp-52ais simply unclamped. In chamber ill the blood passes through the filter screen 44b as it flows in the direction of the front The twice filtered, oxygenated blood then leaves the apparatus by way of blood outlet tube 38'which is connected to an artery of the'recipient.

While the blood passes between filter screens 44a and 44b the force of the flow'tends to push the screens against the back wall- 48 of chamber 11 andthe front wall 32 of chamber i2. This is prevented bymeans'of dimples 3t and 55 of chamber 11 and'dimples 31 and 56 of chamber 12. Carbon dioxide and excess oxygen are vented by means of gas vent 159 in column 10 and gas vents 50 and 51, in chambers 11 and 12, respectively. Additional blood can be added during the oxygenating process by means of passages 35 and 36 and when not in use these passages also serve as gas vents. The approximate blood level in column 10 and chambers 11 and 12 is indicated byline 74 and represents the normal level of operating conditions. If a higher volume of flow is required the oxygenator has the capacity to adapt to such flow by' means of the additional packing material disposed above line 74 and by the enlarged sections in chambers 11 and 12. The enlarged sections, in elfect, provide a much larger reservoir volume Without undue rise of the blood level. Passageway 54 is then employed in addition to passageways 52 and 53 as the means of transferring bloodfrom chamber 11 to chamber 12.

If necessary, and becauseoi its sturdy and rigid construction, the oxygenator can be partially submerged in a bath for the purpose of maintaining temperature con- Another advantage-of construction is that volume as shown inFlGUREl. s

The modified oxygenator 9A of FIGURE 6 1s employed in the exact samemanner as that previously described.

It will be noted'that the novel oxygenator is compact and easily assembled with a minimum of cost. Elficient oxygenation of the blood is effected by means of oxygen disperser generally 39. Maximum contact with the defoaming packing material 17 is maintained by providing conduit at the bottom of column 1%). All oxygenated blood must thereby contact a sufiicient amount of packing17 before it can leave column 10. 'A major portion of packing 17 is above the standpipe portion 14. This provides contact by the blood only to the level determined by the foaming condition. Thus, efficient defoaming action is accomplished without unnecessary contact of the blood with the defoaming agent;

The vertically disposed filter screen generally 41b and a similar screen in chamber 11, a portion of which is this invention. Also, a combination of rigid plastic ma.-

terial can form one half-section of the Walls of the filtering chambers while a softiplastic material could form the other half. The. various inlet and outlet tubes as well as the oxygenating tube 13, can likewise be formed of other flexible plastic or natural materials such as polyethyleneor rubberr A porous polyethylene in place of polyvinylchloride can be utilized in composing oxygenating membrane 27. The filtering screens 44, 44a, 44b, 45, 45b and 71 have been described as being composed of nylon, but other plastic materials such as polypropylene,

polyethylene and high density polyethylene, better known as MARLEX, can also be employed and the same substitution of materials can be made in the instance of the packing material 17.

The above described embodiments being exemplary only, it will be understood that modifications in form or detail can be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be considered as limited save as is consonant with the scope of the following claims.

What is claimed is: J

1. loan apparatus for treating blood, an oxygenating column having means to introduce the blood to be treated into the column and to maintain thesurface level of said blood in said column in excess of a predetermined height, said column also having means to introduce oxygen into the blood in said column and means to discharge carbon dioxide and excess oxygen rising from the surface of said blood; a surface-activedefoaming means in contact with the oxygenated blood in said column; a filter chamber in juxtaposition to said column, said chamber having side walls of a height in excess of the normal level of the blood therein, the portion of said chamber above said level being vented whereby carbon dioxide and oxygen bubbles escaping from the blood in said chamber will be dissipated, said chamber having a filtering screen therein dividing said chamber into two compartments; a passageway between one of said compartments of said chamber and said column, said passageway being at a height to receive blood from said column below the surface levelof the blood therein and to discharge the blood below the surface level of the blood in the chamber; and an outlet connection on said chamber in communication with the other of the compartments below the level of the blood in said other compartment.

2. in an apparatus for treating blood, an oxygenating column having means to introduce the blood to be treated 7 into the column and to maintain the surface level of said blood in said column in excess of a predetermined height, said'column also having means to introduce oxygen into the blood insaid column and means to discharge carbon dioxide and excessoxygen rising from the surface of said blood; a surface-active de ioaming meansin contact with the ox genated blood in said column; a filtering chamber in juxtaposition to said column,'said chamber having side walls of a height in excessofthe normal level of the blood therein, the portion of said chamberjabove said level being vented whereby carbon dioxideand oxygen bubbles escaping from the blood in said chamber will be dissipated, said chamber having a generally vertical filtering screen therein dividing said chamber into two compartments; a passageway betweenoneof said compartments of said chamber and-said column, said passageway being at a height to receive bloodfrom said column below the surface level of the blood therein and to discharge the blood below the surface levelof the bloodin the chamber; and an outlet connection on saidchamber in communication with the other 'of the compartments below the level of the blood in said other compartment.

3. In an apparatus for treating blood, an oxygenating column having'means to introducethe blood to be treated into the column and to maintain thesurface level of said blood in said column in excess. of a predetermined height, said column also having means to introduce oxygen into the blood in said columnand means to discharge carbon dioxide and excess oxygenrising v fromthe surface of said blood; a surface-active, defoaming means in contact with the oxygenated blood in said column; a filtering chamber i in juxtaposition to said column, said chamber having side walls of a height in excess of the normal level of the blood therein, the portion. of said chamber above said level closed and provided with vents whereby carbon dioxide and oxygen escaping from the blood in said chamber will be dissipated, said chamber having a filtering screen therein dividing said chamber into two compartments; a passageway between one of said compartments of said chamber and said column, said passageway being at a height to receive blood from said column below the surface level of the blood therein and to discharge the blood below the surface level of the blood in the chamber; and an outlet connection on said chamber in communication with the other of the compartments below the level of the blood in said other compartment.

4. In an apparatus for treating blood, an oxygenating column having a blood inlet tube to introduce the blood to be treated into the column and to maintain the surface level of said blood in said column in excess of a predetermined height, said column also having an oxygen inlet tube to introduce oxygen into the blood in said column and means to discharge carbon dioxide and excess oxygen rising from the surface of said blood; a surface-active defoaming means in contact with the oxygenated blood in said column; a filtering chamber in juxtaposition to said column, said chamber having side walls of a height in excess of the normal level of the blood therein, the portion of said chamber above said level being vented whereby carbon dioxide and oxygen bubbles escaping from the blood in said chamber will be dissipated, said chamber having a filtering screen therein dividing said chamber into two compartments; a passageway between one of said compartments of said chamber and said column, said passageway being at a height to receive blood from said column below the surface level of the blood therein and to discharge the blood below the surface level of the blood in the chamber; and an outlet connection on said chamber in communication with the other of the compartments below the level of the blood in said other compartment.

5. In an apparatus for treating blood, an oxygenating column having means to introduce the blood to be treated into the column and to maintain the surface level of said blood in said column in excess of a predetermined height, said column also having means to introduce oxygen into the blood in said column and means to discharge carbon dioxide and excess oxygen rising from the surface of said blood; a filtering chamber in juxtaposition to said column, said chamber having side walls of a height in excess of the normal level of the blood therein, the portion of said chamber above said level being vented whereby carbon dioxide and oxygen escaping from the blood in said chamber will be dissipated, said chamber having a filtering screen therein dividing said chamber into two compartments; means to move blood from said column to said chamber without allowing any foam to be carried over, said means including a passageway between one of said compartments of said chamber and said column, said passageway being at a height to receive blood from said column below the surface level of the blood therein and to discharge the blood below the surface level of the blood in the chamber, said means including a quantity of a surface-active material to increase the surface tension of the blood in the foam, said quantity being immersed in the blood and disposed so as to present a relatively large contact area between the material and the blood for the quantity of material present; and an outlet connection on said chamber in communication with the other of the compartments below the level of the blood in said other compartment.

6. In an apparatus for treating blood, an oxygenating column having means to introduce the blood to be treated into the column and to maintain the surface level of said blood in said column in excess of a predetermined height, said column also having means to introduce oxygen into the blood in said column and means to discharge carbon dioxide and excess oxygen rising from the surface of said blood; a filtering chamber in juxtaposition to said column, said chamber having side walls of a height in excess of the normal level of the blood therein, the portion of said chamber above said level being vented whereby carbon dioxide and oxygen escaping from the blood in said chamber will be dissipated, said chamber having a filtering screen therein dividing said chamber into two compartments; means to move blood from said column to said chamber without allowing any foam to be carried over, said means including a passageway between one of said compartments of said chamber and said column, said passageway being at a height to receive blood from said column below the surface level of the blood therein and to discharge the blood below the surface level of the blood in the chamber, said means including a quantity of loose mesh material coated with a blood defoaming agent, said material being immersed in the blood and disposed so as to present a relatively large contact area between the material and the blood for the quantity of said defoaming agent present; and an outlet connection on said chamber in communication with the other of the compartments below the level of the blood in said other compartment.

7. In an apparatus for treating blood, a defoaming column; a permeating tube having liquid and gas inlet means at one end and the other end of said permeating tube communicating with said column; a filter chamber positioned in juxtaposition with said column, said filter chamber having side walls of a height in excess of the normal level of the blood therein, the portion of said chamber above said level being vented whereby carbon dioxide and oxygen bubbles escaping from the blood in said chamber will be dissipated, said chamber having a generally vertical filtering screen therein dividing said chamber into two side-by-side compartments; said filter chamber communicating with said column by means of a conduit disposed in the lower portion of said column and at the lower one side of said filter screen in said chamber; and outlet means communicating with said chamber at the other side of said filter screen in the lower portion of the chamber.

8. In an apparatus for treating blood, an oxygenating tube having blood and oxygen inlet means in communication with one end of said tube; a defoaming column, the other end of said tube communicating with said defoaming column; an oxygenating membrane transversely disposed a short distance inwardly from said one end of said tube having a passageway provided therethrough for said blood inlet tube; a filter chamber positioned in juxtaposition with said column, said filter chamber having side walls of a height in excess of the normal level of the blood therein, the portion of said chamber above said level being vented whereby carbon dioxide and oxygen bubbles escaping from the blood in said chamber will be dissipated, said chamber having a generally vertical filtering screen therein dividing said chamber into two sideby-side compartments; said filter chamber communicating with said column by means of a conduit disposed below said surface level of said blood in said column and at the lower one side of said filter screen in said chamber; and an outlet tube communicating with said chamber at the other side of said filter screen in the lower portion of the chamber.

9. In an apparatus for treating blood, a defoaming column; an oxygenating tube having blood and oxygen inlet tubes in communication with one end; an oxygenating membrane transversely disposed a short distance inwardly from said end of said tube having a passageway provided therethrough for said blood inlet tube, the other end of said tube communicating with the inner lower portion of said column; packing material of a loose mesh construction coated with a blood defoaming agent disposed in said column and surrounding said other end of said tube; a first and a second filter chamber positioned in juxtaposition with said column; a filter screen extending generally vertical in each said filter chamber, said first chamber communicating with said column by means of a conduit disposed in the lower portions of said column and said first chamber at one side of saidfilter screen in said chamber; at least one passage- Way Communicating with first and second'filter chambers, said passageway communicating with said first chamber at the other side of said filter screen in said chamber, said passageway also communicating with said second chamber at one side of said filter screen in said second chamber; and an outlet tube communicating with said second chamber at the other side of said filter screen in the lower portion thereof. 7

10. In an apparatus for treating blood, a defoaming column; an oxygenating tube having blood and oxygen inlet tubes in communication with one end; an oxygenating membrane transversely disposed a short distance inwardly from said end of said tube having a passageway provided therethrough for said blood inlet tube, the other end of said tube extending longitudinally a sub-' stantial distance inwardly into said column in the base portion and in axial alignment with said column to form a standpipe portion, therein; packing material of a loose mesh construction coated with a blood defoaming agent disposed in said column and surrounding said standpipe portion; a first and a second filter chamber, saidfirst chamber laterally attached to said column and to said second chamber, said chambers positioned in' juxtapositionwith respect to said column, said first and said second chambers having oppositely disposed walls; two filter screens composed of a supporting frame and filtering screen material secured-within said frame, said filter screens accommodated between the walls of each said chamber, said first chamber communicating with said column by means of a conduit disposed in the' lower portions of said column and said first chamber and contacting said first chamber between one wall, and said screen; at least one passageway communicating between said chambers'at a point between-the other wall of said first chamber and the other side of said screen, and between the adjacent wall of'said second chamber and said screen in said second chamber; and an outlet tube communicating with said second chamber through said other wall of said second chamber in the lower portion thereof. 7

11. In an apparatus for treating blood, a defoaming column; an oxygenating tube having blood and oxygen inlet tubes in communication with one end; an oxygenating membrane transversely disposed ashort distance inwardly from said end of said tube having a passageway provided therethrough for said blood inlet tube, the other end of said tube extending longitudinally a substantial distance inwardly into said column in the base portion and in axial alignment with' said'column to form a standpipe portion therein; packing material of a loose mesh construction coated with a blood defoaming agent disposed in said column and surrounding said standpipe portion; a first and a second filter chamber, said first chamber laterally attached to said column and to said second chamber; said chambers positioned in juxtaposition with respect to 'said column, said first and wardly from said end of said tube having a passageway provided therethrough for said blood inlet tube, the other end of said tube extending longitudinally a substantial distance inwardly into said column in the base portion and in axial alignment with said column to form a standpipe portion therein; packing material of a loose mesh construction coated with a blood defoaming agent substantially. filling said column and surrounding said standpipe portion; a first and a second filter chamber, said first chamber laterally attached to said column and to said second chamber, said chamoers positioned in juxtaposition with respect to said column, said first and second chambers having front and rear'walls; filter screens composed of a supporting frame and filtering screen'material secured within said frame; said filter screens accommodated between the front and rear walls of each said chamber, said first chamber communicatingwith said column by rneans'of a conduit disposed in the lower portions of said column and said first chamber and contacting said firstchamber between said front wall and said screen; a first normally closed passageway communicating between said chambers at a point between the other wall of said first chamber and said screen and the rear wall of said second chamber and said screen in said second chamber at a 'short distance from the bottom of said chambers; a

second passageway extendin g'in a similar manner as said first passageway a short distance above said first passageway; and a third passageway extending in a similar manner as said first passageway approximately midway between the top and bottom of said chambers; and an outlet tube communicating with said second chamber through said front wall of said second chamber in the lower portion thereof.

13. In an apparatus for treating blood, a defoaming column; an oxygenating tube having blood and oxygen inlet tubes in communication with one end; an oxygenating membrane transversely disposed a short distance inwardly from said end of saidtube having a passageway provided therethrough for said blood inlet tube, the other end of said tube extending longitudinally a substantial distance inwardly into said column in' the base portion and in axial alignmentwith said column to form a standpipe portion therein; packing material of a loose mesh construction coated with a blood ,defoarning agent substantially filling said column and surrounding said standpipe portion; a first and a second filter chamber, said first chamber laterally attached to said column and to said second chamber, said chambers positioned in juxtaposition with respect to said column, said first and second chambers having front and rear walls diverging outwardly from the top to form the largest cross-section for the chamber at a point midway from the top and bottom thereof and converging again as they approach the bottom of the chamber where said walls are substantially parallel;

two-filter screens composed of a supporting frame and said second chambers having oppositely disposed walls; 7 V

a unitary sheet of filter material secured between said oppositely disposed walls of said chambers, said first chamber communicating with said column by means of a conduit disposed in the lower portions of said column and said first chamber and contacting said first chamber between one wall and said screen of said first chamber; at least one passageway communicating betweenrsaid chambers at a point between the other wall of 'said first chamber and the adjacent wall of said second chamber and said screen in second chamber; and an outlet tube communicating with said second chamber through said other wall of said second tion thereof. 7

12. In an apparatus for treating'blood, a defoaming column; an oxygenating tube having bloodrand oxygen inlet tubes in communication with one end;-an oxygenatchamber in the lower porfiltering screen material secured within said frame, said filter screens accommodated between the front and rear walls of each said chamber, said first chamber communicating withisaid column by means of a conduit disposed in the lower'portions of said column and said first cham ber and contacting said first chamber between said front wall and said screen; a first normally closedpassageway communicating between said chambers at a point between the other wall of said first'chamber and said screen and the rear wallof said second chamber and said screen in said second chamber at a short distance from the bottom of jsaid'chambers; a secondrpassa'geway extending in a similar manner as said first passageway a short distance above said first passageway; a third passageway extending in a similar manner as said first passageway approximately midway between the top and bottom of said chambers at I the point of largest cross-section; an outlet tube communieating with said second chamber through said front wall of said second chamber and'the lower portion thereof; at

least one gas vent disposed in the upper portions of said rear walls of said chambers; at least one auxiliary blood inlet passageway in the upper portions of said front wall of said first chamber, filtering means on said vent and said inlet; and oppositely disposed dimples in the lower portions of said front and rear walls of said chamber whereby the screen is retained away from said walls.

14. The invention defined in claim 13 wherein the defoaming column and the filter chambers are composed of a rigid polyvinylchloride material, the blood and oxygen inlet tubes, the oxygenating tube and the blood outlet tube are of a flexible polyvinylchloride material, the oxygenating membrane of a porous, polyvinylchloride material, and the packing material is composed of Saran.

15. In an apparatus for treating blood, a device for oxygenating blood; a passageway connected to said device to receive the oxygenated blood therefrom; and a chamber to receive the oxygenated blood to a depth in excess of a predetermined level, said chamber having walls rising to a height in excess of said level, said chamber including a filtering screen therein dividing said chamber into two side-by-side compartments, and at least a substantial portion of said screen being below said level, said chamber being connected to said passageway with the passageway being in communication with one of said compartments at a point below said level, said chamber having a discharge opening communicating with the other of the compartments.

16. In an apparatus for treating blood, a device for oxygenating blood; a passageway connected to said device to receive the oxygenated blood therefrom; a first and a second chamber to receive the oxygenated blood to a depth in excess of a predetermined level, said chambers having walls rising to a height in excess of said level, said chambers including a filtering screen therein dividing said chambers into two compartments, at least a substantial portion of said screen being below said level, said first chamber being connected to said passageway with the passageway being in communication with one of said compartments of said first chamber at a point below said level, and a passageway communicating between said chambers with the other compartment of said first chamber and one compartment of said second chamber, said second chamber having a discharge opening communicating with the other of the compartments.

17. In an apparatus for treating blood, a device for oxygenating blood; a passageway connected to said device to receive the oxygenated blood therefrom; a first and a second chamber to receive the oxygenated blood to a depth in excess of a predetermined level, said chambers having walls rising to a height in excess of said level, said chambers including a filtering screen therein dividing said chambers into two compartments, at least a substantial portion of said screen being below said level, said first chamber being connected to said passageway with the passageway being in communication with one of said compartments of said first chamber at a point below said level, a passageway communicating between said chambers with the other compartment of said first chamber and one compartment of said second chamber, said second chamber having a discharge opening communicating with the other of the compartments, and means for spacing said filtering screens from said walls.

18. In an apparatus for treating blood, a device for oxygenating blood; a passageway connected to said device to receive the oxygenated blood therefrom; a chamber to receive the oxygenated blood to a depth in excess of a predetermined level, said chamber having walls rising to a height in excess of said level, said chamber including a filtering screen therein dividing said chamber into two compartments, at least a substantial portion of said screen being below said level, said chamber being connected to said passageway with the passageway being in communication with one of said compartments at a point below said level, said chamber having a discharge opening communicating with the other of compartments below said level; and defoaming means submerged in the blood between the device and the chamber including a quantity of a surface-active material to increase the surface tension of the blood in the foam, said quantity being disposed so as to present a relatively large contact area between the material and the blood for the quantity of material present.

19. In an apparatus for treating blood, a first filter chamber and a second filter chamber, venting means venting each of said chambers to the ambient said first and second filter chambers each having a filter screen to divide each of said chambers into two compartments, inlet conduit means leading from a source of oxygenated blood to one compartment of said first filter chamber, a passageway leading from the other compartment of said first filter chamber to one compartment of said second filter chamber and disposed sufiiciently above said inlet conduit to effect filtering, and an outlet conduit leading from the other compartment of said second chamber.

20. In an apparatus for treating blood, a first filter chamber and a second filter chamber, venting means venting each of said chambers to the ambient said first and second filter chambers each having a filter screen to divide each of said chambers into two compartments, inlet conduit means leading from a source of oxygenated blood to one compartment of said first filter chamber, a passageway leading from the other compartment of said first filter chamber to one compartment of said second filter chamber and disposed sufficiently above said inlet conduit to effect filtering, a conduit providing communication between said other compartment of said first filter chamber and said one compartment of said second filter chamber at a place below said passageway and near the bottoms of said filter chambers, means for selectively allowing and shutting-off fiow through said conduit, and an outlet leading from the other compartment of said second chamber.

References Cited in the file of this patent UNITED STATES PATENTS 777,159 Tunbridge Dec. 13, 1904 2,683,117 Rosenak et al. July 6, 1954 2,934,067 Calvin Apr. 26, 1960 FOREIGN PATENTS 56,582 Germany May 5, 1891 OTHER REFERENCES Shumway et al.: A Mechanical Pump-Oxygenator for Successful Cardio-Pulmonary By-Pass, from Surgery, vol. 40, #5, November 1956, pp. 831-839.

Rygg et al.: A Disposable Polyethylene Oxygenator System, from Acta Cherurgiva Scandinavica, vol. 112, #6, pp. 434436.

Gilman et al.: An Air Trap Filter for Extracorporeal Oxygenator Systems, from Surgery, vol. 42, #6 December 1957, pp. 993-5. 

1. IN AN APPARATUS FOR TREATING BLOOD, AN OXYGENATING COLUMN HAVING MEANS TO INTRODUCE THE BLOOD TO BE TREATED INTO THE COLUMN AND TO MAINTAIN THE SURFACE LEVEL OF SAID BLOOD IN SAID COLUMN IN EXCESS OF A PREDETERMINED HEIGHT, SAID COLUMN ALSO HAVING MEANS TO INTRODUCE OXYGEN INTO THE BLOOD IN SAID COLUMN AND MEANS TO DISCHARGE CARBON DIOXIDE AND EXCESS OXYGEN RISING FROM THE SURFACE OF SAID BLOOD; A SURFACE-ACTIVE DEFOAMING MEANS IN CONTACT WITH THE OXYGENATED BLOOD IN SAID COLUMN; A FILTER CHAMBER IN JUXTAPOSITION TO SAID COLUMN, SAID CHAMBER HAVING SAID WALLS OF A HEIGHT IN EXCESS OF THE NORMAL LEVEL OF THE BLOOD THEREIN, THE PORTION OF SAID CHAMBER ABOVE SAID LEVEL BEING VENTED WHEREBY CARBON DIOXIDE AND OXYGEN BUBBLES ESCAPING FROM THE BLOOD IN SAID CHAMBER WILL BE DISSIPATED, SAID CHAMBER HAVING A FILTERING SCREEN THEREIN DIVIDING SAID CHAMBER INTO TWO COMPARTMENTS; A PASSAGEWAY BETWEEN ONE OF SAID COMPARTMENTS OF SAID CHAMBER AND SAID COLUMN, SAID PASSAGEWAY BEING AT A HEIGHT TO RECEIVE BLOOD FROM SAID COLUMN BELOW THE SURFACE LEVEL OF THE BLOOD THEREIN AND TO DISCHARGE THE BLOOD BELOW THE SURFACE LEVEL OF THE BLOOD IN THE CHAMBER; AND AN OUTLET CONNECTION ON SAID CHAMBER IN COMMUNICATION WITH THE OTHER OF THE COMMPARTMENTS BELOW THE LEVEL OF THE BLOOD IN SAID OTHER COMPARTMENT. 